Our research coordinates the analysis of individual mobility differentials with the analysis of population redistribution within and among regions. We will analyze the spatial mobility of the U.S. population and trends in population redistribution over the period 1940-80, based on census and other data. The work will provide comprehensive descriptive information about differentials in mobility propensity for population subgroups, changes over time in these differentials, trends in population redistribution. Discrete choice and hazard models of mobility process will also be developed, allowing inferences concerning changes in the behavioral structure of mobility, and how these relate to aggregate patterns of migration. Initially, our efforts will be divided into two subprojects. One focuses on the mobility choices of individuals, examining the determinants of mobility, integrating the analysis of local and long distance movement. The other examines population redistribution, focusing on aggregate migration statistics for U.S. counties. It applies a new model that more aptly reflects the cumulative impact of individual migrant choices, facilitating explicit hypothesis tests about the role of migrant preferences in aggregate migration, as well as accounting for economic and environmental characteristics of places. Finally, we integrate the two subprojects, developing structures that allow simultaneous estimation of the effects of personal characteristics and the characteristics of locations--those of the origin and potential destinations--on the mobility of individuals and the aggregate redistribution of population.